This invention relates to an improvement in the fabrication and operation of multi-stage compressors to achieve increased efficiency by cooling the compressed gas in at least a portion of the stages and by cleaning the rotors in at least a portion of the stages by the injection of cleaning chemicals via nozzles used for the injection of a cooling fluid into at least a portion of the stages.
In many industrial applications such as the use of turbines to generate electrical power and the like, it is necessary that large volumes of gas, such as air, be compressed to relatively high pressures. While various types of gases such as hydrogen, natural gas, and the like are frequently compressed, the present invention will be discussed primarily by reference to the compression of air, although it is also useful with other gases. Large quantities of air are typically compressed for use for the combustion of natural gas or the like to provide a gaseous steam for use in driving turbines to generate electricity.
When gases are compressed, it is well known that the temperature of the compressed gas increases as the pressure is increased. In some instances, when high pressures are desired, it has been necessary to use a first compressor followed by inter-stage cooling and subsequent compression in a second compressor to reach the desired compression levels within temperature limitations of the compressors. In some instances, more than two compression stages have been required.
The use of such inter cooler steps has not generally been considered feasible for multi-stage compressors, particularly axial compressors comprising a plurality of stages with each stage comprising a set of rotor blades and a set of stator blades which have been used to compress air for use in the generation of electricity. Axial compressors have been the preferred types of compressor for this application.
A further problem in maintaining the capacity of compressors used for such purposes has been the tendency of the compressor blades to foul. This results in a substantial loss of power in the compressor. Various techniques have been used in attempts to clean the blades and avoid the loss of power. Some such techniques are discussed in xe2x80x9cGas Turbine Compressor Washing State of the Artxe2x80x94Field Experiences,xe2x80x9d by Jean Pierre Stadler, The American Society of Mechanical Engineers, 98-GT-420, 1998. In this article various techniques have been discussed for cleaning deposits from the blades of compressors. It appears that the cleaning solutions were introduced via the air inlet to the compressors.
As a result of the large amount of air required for electrical power generation as well as the requirements for large volumes of other gases, a continuing search has been directed to the development of a method and a compressor design, which can more efficiently compress gases.
According to the present invention, increased efficiency in such compressors can be achieved by a method for increasing the efficiency of the compression in a multi-stage compressor by injecting a quantity of a finely-divided mist of a selected liquid into at least one stage of the compressor to reduce the temperature of a compressed gas in the at least one stage thereby permitting the compression at an increased efficiency.
The invention further comprises an improved multi-stage compressor which includes a plurality of nozzles positioned to inject a quantity of a finely-divided mist of a selected liquid into at least one stage of the compressor to reduce the temperature of a compressed gas stream in at least one stage thereby enabling more efficient compression of the compressed gas and a reduction in the compressor power requirement.
The invention further comprises a multi-stage gas compressor comprising: an outer housing having an inside and an outside, an inlet and an outlet and supporting on its inner surface a plurality of rows of stator blades arranged around the inside of the outer housing; a rotor rotatably positioned inside the outer housing, having an outside, a first end near the inlet of the outer housing and a second end near the outlet of the outer housing and a plurality of rows of rotor blades arranged around the outside of the rotor with at least a portion of the rows of rotor blades being between the rows of stator blades, each row of the rotor blades with a succeeding row of stator blades forming a single compressor stage; and, at least one mist injection nozzle positioned to inject a selected quantity of a finely-divided mist of a selected liquid into the compressor between at least one pair of the stator blades in at least one of the rows of stator blades in at least one stage to enable more efficient compression of a compressed gas.
The invention further comprises a method for increasing the compressor efficiency in a multi-stage gas compressor comprising: an outer housing having an inside and an outside, an inlet and an outlet and supporting on its inner surface a plurality of rows of stator blades arranged around the inside of the outer housing; a rotor rotatably positioned inside the outer housing, having an outside, a first end near the inlet of the outer housing and an outlet near the outlet of the outer housing and a plurality of rows of rotor blades arranged around the outside of the rotor, each row of rotor blades taken with a succeeding row of stator blades forming a single compressor stage; and, at least one mist injection nozzle positioned to inject a selected quantity of a finely-divided mist of a selected liquid into the compressor between at least one pair of the stator blades in at least one of the rows of stator blades.